Semiconductor devices such as multiple semiconductor integrated circuits formed on each chip region of a semiconductor wafer undergo a current test to determine whether or not each of them is produced according to its specification. In this type of current test is used a probe assembly generally called probe card. When the plural probes (contacts) provided on a probe board of this probe assembly are pressed against their corresponding electrodes of a device under test, the device under test is connected to a tester through the probe assembly.
In this probe assembly, the probe is connected to each attaching land portion provided at a wiring circuit of the probe board.
In a conventional production of a probe assembly, lead-free cream solder containing multiple solder balls having a particle diameter of, e.g., 15-25 μm are generally used to adhere each probe to each corresponding attaching land portion of the probe board. The cream solder is supplied to connecting end portions of the probes by spraying. The probes to which the cream solder adhered are held at a predetermined attitude such that their connecting end faces abut the land portion of a probe board. In this held state, a laser beam is applied to the connecting end portion of the probe, melting the solder by its thermal energy, and solidification of the melted solder makes each probe fixed on the corresponding land portion.
It is, however, very difficult to apply a proper amount of cream solder to the connecting end portion of each probe by spraying. As shown in FIG. 4(b), if the amount of the solder 3 is short in combining the probe 1 and the wiring land portion 2, connection strength becomes too low to obtain a desired connection strength. On the other hand, as shown in FIG. 4(c), excessive solder 3 sticking out largely from the wiring land portion 2 causes a short-circuit between the adjacent probes, and the excessive solder scattering around causes a contamination problem to probe handling instruments. Thus, the supply of the excessive solder brings about various inconveniences.
It is, therefore, proposed to plate the connection end face of the probe with tin as the solder, and to fix the probe on the probe board by a metal compound formed by melting together with a gilded layer formed on a contact mounting face of the probe board (see Patent Document 1).
According to this, since the solder is supplied beforehand to the connecting end face of each probe as tinned layer of the probe, the solder is not supplied excessively between the probe and the probe board. This can dissolve the problem of excessive supply of the solder.
However, since the tin to be formed on the probe connecting end face is formed by plating, the thickness of the layer is under severe restrictions. Furthermore, since the area of the connecting end face is small, the connecting end face cannot be enlarged without large-sizing the probe. Therefore, since it is not possible, by the technique described in the Patent Document 1, to hold a proper amount of solder enough to pass around behind both its side portions of the end face of the probe connection portion, an amount of solder sufficient to obtain a desired connecting strength cannot be supplied to the connection portion of the probe between the probe and the probe board.
Patent Document: Japanese Patent Appln. Public Disclosure No. 2005-55194